This invention relates to a process for preparing a bisimide of the formula, ##STR1##
This bisimide has been found to be a useful flame retardant in polyesters, e.g. polybutylene terephthalate, and other resin formulations.
While various processes have been described for the preparation of this bisimide, there is a need for a process which gives the bisimide product in high yield and in highly pure form.